[Zenji]

Hello Oz zoners,

Just wanting your know how for running home cnc / large single phase machinery with regards to power usage.

What times of day?
Weekends?

This carbon tax makes power really expensive, almost to the point of running a petrol generator.

How are you guys coping?

Cheers,

Derek.

[RCaffin]

This carbon tax makes power really expensive

Waffle. Total waffle.
Any increases on pricing have been mainly due to provision for infrastructure upgrades - and have been labeled gold-plating by some. On the other hand, others have said 'about time' for the infrastructure work. I tend to agree with the latter. The impact of the carbon tax has been almost invisible.

Cheers

[denz]

This could get interesting:argue:

[tgdavies]

I agree that the carbon tax has little to do with it.

The other factor is that there is no fixed charge for domestic electricity -- so if total demand falls (e.g. due to conservation due to increased prices, or domestic pv) the cost of the infrastructure is spread over fewer KWhrs of billing. That's not really fair as the total cost of infrastructure is determined more by peak usage, and even someone with low average usage (due to their own solar) may have peak usag as high as everyone else.

I think my CNC operating cost is dominated by the end mills I break, not my electricity usage :-)

[RCaffin]

I think my CNC operating cost is dominated by the end mills I break, not my electricity usage :-)

Yeah!
Plus the cost of trying to 'repair' a servo driver which was not actually faulty, just built slightly wrong.

Mind you, raw materials here in Oz are not cheap either.

Then there are the 'upgrades' as well ...

Cheers

[Zenji]

I'll take RCaffins comment with a grain of salt, the setup I plan to run will draw alot off current, 3 * 5 amp motors through a large unregulated power supply.

It might be overkill for a benchtop, I'm guessing it'll use similar power to an electric oven.

By the way, I do believe we pay some of the highest energy costs in the developed world.

I suppose it's like baking a cake - using a cnc at home - 1 1/2 hrs a day tops, maybe not so bad.

I wanted to hear if anybody has issues.

[RCaffin]

I'll take RCaffins comment with a grain of salt, the setup I plan to run will draw alot off current, 3 * 5 amp motors through a large unregulated power supply.

So the rating is a max of 15 A at, what, 48 V? (I have no idea, but I am assuming steppers.) That's 720 W.
However, while my motors are rated at something like 8 A and 48V for the axes and 10 A / 80 V for the spindles, I would point out that typically they draw maybe 200 - 300 mA. (I have meters on the supplies.)

> It might be overkill for a benchtop, I'm guessing it'll use similar power to an electric oven.
Unlikely! A single hotplate might draw 2.4 kW. Run several together and you ARE talking power. But a little CNC?

Cheers
Roger

[aarggh]

I'd be more concerned at the cost of water supply here than the cost of running my CNC these days. I don't notice any amount of significance on my electricity bill when using the mill or cnc machine for any period.

I do notice the costs when the air con is used though, like today which seems a tad warm!

cheers, Ian

[bushwakka]

Zenji,

The power bill for my whole shed that houses the router is less than $250/qtr. Router runs 1-3hours most days.
Just think of it as part of the cost of the hobby.
The biggest part of my load is the dust extractor (2.2kW motor running at somewhere around 1.5-2kW or roughly 50c/hour.)
The router (8x4, 3x400W servos, with 2.2kW spindle, 1/2hp waterpump for cooling water, computer and monitor) runs off a 10A circuit so about the same or less than the dust collector.

My business is generators, and there is no way at all you can produce your own electricity for less than the grid. Running a small diesel generator will cost you upwards of 80c/kWh in diesel (plus servicing costs, and the cost to buy). A petrol generator uses about twice the fuel, and is noisier than your router. Normal electricity prices are less than 30c/kWh single rate tarriff, around 45c/kWh peak Time of Day Tarriff.

If you want to offset the electricity cost you could possible install solar panels and get them connected as Nett metering, then only use your router when its sunny.
Or you could set up a solar system that charges 48V battery bank and use that for running your stepper motors.
But really, you are better off spending your thinking time of ideas to upgrade your router, and things to cut, and as other have suggested, make sure your don't wreck endmills prematurely.

Cheers
Bushwakka

[RussellK]

Like many, I don't even know where to start with this one. Blaming the "carbon tax" for the cost of running what sounds like a pretty small CNC machine is profoundly mis-informed.

First point: there is no carbon tax. We don't have one. We actually have an emissions trading scheme with a fixed price that is moving to a floating price in a couple of years (brought forward to a year before the last election).

Second point: what people refer to as a "carbon tax" has had one-poofteenth of a percent impact on retail prices. Its actual effect has been the decommissioning of the filthiest, old, dirty coal power generators with increased investment in far cleaner, efficient tri-generation gas plants and other more efficient generation.

Third point: by far the biggest impact on retail power price has been the so-called "gold plating" of the distribution network. This has been blamed on perverse incentives for distributors to do so, but is also a response to the ever-growing peak loads confronted by the network. The fundamental problem is that the public have zero tolerance for brown-outs or load shedding, so the network has to be designed to cope with the very worst scenario, which is after sundown during a heat wave that's lasted a few days. At that point homes have accumulated a great deal of heat in their structures, and everyone switches on their A/C to cool their house in the warm evening. There's no solar generation to offset the load - the network and generation has to hold up the voltage - no brownouts allowed, no load-shedding allowed.

All that infrastructure and capacity in place just to cover maybe half a dozen events a year. Rest of the time the demands are far lower, but all the gear has to be there.

In short, if you want to know why power prices are so high, look at all the split-system A/C's installed in your suburb.

Which is also why if the price on carbon is removed, you won't see a long-term (ie. greater than a year) reduction in your power price. Far greater costs are in play.

In the mean time, purchase a plug-in wattmeter for your CNC setup. It'll tell you exactly what your setup costs to run.